This U.S. nonprovisional patent application claims priority under 35 U.S.C. § 119 from Korean Patent Application 2002-43541, filed Jul. 24, 2002, Korean Patent Application 2003-28980, filed May 7, 2003, and Korean Patent Application 2003-31400 filed May 17, 2003, the entire contents of which are hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a film carrier tape for a semiconductor package and a manufacturing method thereof and, more particularly, a film carrier tape having a reinforcing film for increasing the strength of the film carrier tape.
2. Description of the Prior Art
As electronic devices become miniaturized and multi-functional, the semiconductor packages used in the electronic devices also need to be smaller. Several types of packages have been developed in response to this demand including tape carrier packages (TCP) and chip-on-film packages (COF). Both tape carrier packages and chip-on-film packages are manufactured using a thin film rather than a lead frame or a printed circuit board (PCB) for mounting the semiconductor chips. For mass production of TCP or COF, a film carrier tape on which a plurality of packages may be formed is typically used.
The structure of a conventional film carrier tape will be described with reference to FIGS. 1-3. FIG. 1 is a perspective view of a conventional film carrier tape (10) comprising a base film (100), a wiring pattern (154) formed on the upper side of the base film (100) and a reinforcement metal pattern (152). The base film (100) comprises a main area (110) through which a chin installation hole 112 is formed and on which the wiring pattern (154) is formed, and a peripheral area (120) on which a plurality of sprocket holes (122) is formed.
The sprocket holes (122) are used for transporting the film carrier tape by a rotating sprocket. The reinforcement metal pattern (152) is formed on the peripheral area (120) of the base film (100) to reduce the likelihood that the sprocket holes (122) will be torn by the sprocket teeth (not shown), and to enhance the strength of the base film (100). The base film (100) is usually made of one or more layers of synthetic resin such as polyimide, and may have a thickness of about 38 μm.
The wiring pattern (154) and the reinforcement metal pattern (152) are usually made of conductive metals such as copper (Cu), and may have a thickness of about 8 μm. The wiring pattern (154) and the reinforcement metal pattern (152) can be made by patterning and etching a thin metal layer formed on the base film (100).
In a typical manufacturing process, a film carrier tape having two or more lanes of films may be used to enhance the efficiency of the manufacturing process. FIG. 2 is a perspective view showing a film carrier tape having two lanes of film that can be used in a conventional manufacturing process.
As shown in FIG. 2, each of the lane's film (15) has a width (A), typically 35 mm, and are formed on a film carrier tape (30) having a width (B), typically 105 mm, for use in the conventional manufacturing process.
The metal layer (150) which will be patterned and etched to form the wiring pattern and the reinforcement metal pattern is formed on the upper surface of a base film (105). A supplementary film (130) may be attached to the lower surface of the base film (105).
In order to form the uniform reinforcement metal pattern and the wiring pattern, a liquid photoresist needs to be applied evenly across the metal layer (150) on the base film (105). However, the liquid photoresist applied on the outermost peripheral areas of the film carrier tape (30) runs down through the outermost sprocket holes (160) which were formed before the patterning and etching process to provide for the transfer of the film carrier package. Therefore, the area of base film (105) near the sprocket holes (160) cannot be used and are wasted. The sprocket holes (132) of each lane of the films (15) are formed after the photoresist becomes hardened. Therefore, although three lanes of film could be formed on the film carrier tape given the typical widths of each lane of the film (15) and the film carrier tape (30), only two lanes of film can be formed on the film carrier tape in the conventional manufacturing process.
The supplementary film (130) usually includes one or more synthetic resins such as polyethylene terephthalate (PET), and may have a thickness of about 50 μm. After manufacturing the film carrier tape (30), the supplementary film (130) may be removed from the lower surface of the base film (105).
A solder resist layer is usually formed on the metal layer (150) of the film carrier tape (30), to a thickness of about 12 μm in order to reduce oxidization of the metal layer (150).
FIG. 3 shows the result of a computer simulation of the deformation of the conventional film carrier tape under pressure. As shown in FIG. 3, the deformation of the film carrier tape is greatest near the surface on which the sprocket directly exerts force despite the reinforcement metal pattern provided on the peripheral area of the film.
In addition, the sprocket holes may be easily torn by the sprocket, because the reinforcement of the reinforcement effect of the conventional reinforcement metal pattern is not sufficient.
In addition, a large amount of films are wasted for forming the reinforcement metal pattern by the above-describe reason.